Import Question JSON

Current Question (ID: 8469)

Question:

$\text{The ionisation constant of an acid, } K_a\text{, is the measure of the strength of an acid. The } K_a \text{ values of acetic acid, hypochlorous acid and formic acid are } 1.74 \times 10^{-5}\text{, } 3.0 \times 10^{-8} \text{ and } 1.8 \times 10^{-4}\text{, respectively. The correct order of pH value of } 0.1 \text{ mol dm}^{-3} \text{ solutions of these acids is:}$

Options:

1. $\text{Acetic acid} > \text{Hypochlorous acid} > \text{Formic acid}$
2. $\text{Hypochlorous acid} < \text{Acetic acid} > \text{Formic acid}$
3. $\text{Formic acid} > \text{Hypochlorous acid} > \text{Acetic acid}$
4. $\text{Formic acid} < \text{Acetic acid} < \text{Hypochlorous acid}$

Solution:

$\text{HINT: } K_a \propto \text{acidity} \propto \frac{1}{\text{pH}}$ $\text{Explanation:}$ $\text{As the acidity or } K_a \text{ value increases, pH decreases, thus, the correct order of pH value of the acids is:}$ $\text{Hypochlorous acid} > \text{acetic acid} > \text{formic acid}$ $(3.0 \times 10^{-8}) \quad (1.74 \times 10^{-5}) \quad (1.8 \times 10^{-4})$

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Upload a JSON file containing LaTeX/MathJax formatted question, options, and solution.

Expected JSON Format:

{
  "question": "The mass of carbon present in 0.5 mole of $\\mathrm{K}_4[\\mathrm{Fe(CN)}_6]$ is:",
  "options": [
    {
      "id": 1,
      "text": "1.8 g"
    },
    {
      "id": 2,
      "text": "18 g"
    },
    {
      "id": 3,
      "text": "3.6 g"
    },
    {
      "id": 4,
      "text": "36 g"
    }
  ],
  "solution": "\\begin{align}\n&\\text{Hint: Mole concept}\\\\\n&1 \\text{ mole of } \\mathrm{K}_4[\\mathrm{Fe(CN)}_6] = 6 \\text{ moles of carbon atom}\\\\\n&0.5 \\text{ mole of } \\mathrm{K}_4[\\mathrm{Fe(CN)}_6] = 6 \\times 0.5 \\text{ mol} = 3 \\text{ mol}\\\\\n&1 \\text{ mol of carbon} = 12 \\text{ g}\\\\\n&3 \\text{ mol carbon} = 12 \\times 3 = 36 \\text{ g}\\\\\n&\\text{Hence, 36 g mass of carbon present in 0.5 mole of } \\mathrm{K}_4[\\mathrm{Fe(CN)}_6].\n\\end{align}",
  "correct_answer": 4
}